1. Field of the Invention
The invention relates to a photoresist developing nozzle, a photoresist developing apparatus, and a photoresist developing method, more in detail, it relates to a photoresist developing nozzle, a photoresist developing apparatus, and a photoresist developing method for use in a lithography process in fabricating integrated circuits.
Particularly, the invention relates to a photoresist developing nozzle, a photoresist developing apparatus, and a photoresist developing method to be suitably used in fabricating integrated circuits employing a large diameter wafer.
2. Related Art
Integral circuits such as an IC, an LSI and a ULSI are ordinarily fabricated by photolithography.
An example of a photoresist developing apparatus which has been conventionally used in a developing process in the photolithography is shown in FIG. 14.
As shown in FIG. 14, a conventional photoresist developing apparatus comprises generally a photoresist developing nozzle A for discharging developer downward so as to put the developer on the surface of a wafer W to be developed, a turntable B which are disposed under the photoresist developing nozzle A so as to oppose the photoresist developing nozzle A for placing a wafer W thereon and turning it, and a developing cup C for preventing developer put on the wafer W from scattering toward the periphery of the wafer W.
The photoresist developing nozzle A comprises a columnar or pillar-shaped nozzle body A2 which is disposed horizontally and is hollow at the interior thereof, developer discharge sections A4 comprised of a plurality of sections arranged longitudinally and disposed at one face of the nozzle body A2 facing the turntable B for discharging developer downward, a developer supply pipe A6 disposed substantially at the center of the nozzle body A2 for supplying developer inside the nozzle body A2, and a nozzle transfer driving section A8 for moving the nozzle body A2 horizontally and vertically as depicted by the arrows b and c in FIG. 14, and holding the nozzle body A2 at a given position immediately over the wafer W placed on the turntable B during development. The nozzle body A2 has a length which is substantially the same as the diameter of the wafer W.
The photoresist developing apparatus is further provided with a rinse nozzle D for rinsing away the wafer W after discharging cleansing water on the wafer W after development. The rinse nozzle D is held at the position where it is avoided or moved away from the photoresist developing nozzle A and the wafer W so that it does not impede the motion of the photoresist developing nozzle A and so forth and is moved over the wafer W when rinsing away the wafer W.
However, since the discharging amount of developer discharged from the photoresist developing nozzle A is controlled by a supply pressure of developer in the developer supply pipe A6, it has been difficult to control the discharging amount and discharging pressure of developer with high accuracy across the entire length of the nozzle body A2.
Further, since the temperature of the developer supplied from the developer supply pipe A6 is normally lower than that of the interior of a clean room where the wafer W is developed, it increases as it directs from the central portion of the nozzle body A2 to the end portions thereof. Accordingly, the temperature of the developer discharged from the developer discharge sections A4 at the end portions of the nozzle body A2 is prone to be higher than that at the central portion of the nozzle body A2.
Since photoresist is easily molten as the temperature of the developer becomes high, the size of the resist pattern becomes small. For example, in the case of employment of a product called as WKR-PT-2 as a photoresist manufactured by Wako Junyaku Kogyo Kabushiki Kaisha and 2.38% water solution of tetramethyl ammonium hydroxide as a developer, an exposure is effected under the condition that the width of a resist pattern becomes 0.3 xcexcm when the liquid temperature of the developer is 22xc2x0 C., and development is effected at 24xc2x0 C. instead of 22xc2x0 C. As a result, the width of the resist pattern becomes small to an extent ranging from 0.27 to 0.28 xcexcm.
As high degree of integrity has been recently required for integrated circuits, the integrated circuits have been fabricated in a design room of 0.15 xcexcm, so that it has been more and more strongly required that variations in width of a resist pattern at positions between the central portion and the peripheral portion of the wafer are small.
Nevertheless, as the diameter of the wafer increases from 8 inch to 12 inch, it is necessary to use the long nozzle body A2 having a long length so that a temperature of the developer at the central portion of the nozzle body is largely different from that at the end portions thereof.
Accordingly, as the diameter of the wafer increases, there has arisen a serious problem that there occur frequently variations in a width of a resist pattern at the positions between the central portion of the wafer and the peripheral portion thereof such that a resist pattern at the central portion of the wafer becomes large and that at the periphery thereof becomes small.
Since spots where developer is not put on a wafer coated with photoresist which is prone to repel developer are liable to be produced, it is necessary to discharge developer as much as possible at the portion where the developer is liable to be repelled. Further, it is impossible to control the discharging amount of developer for every developer discharge section independently of each other, it has been necessary to increase the amount of supply of the developer from the developer supply pipe to prevent the production of spots where the developer is not put on the wafer.
Further, if the amount of supply of the developer from the developer supply pipe is increased, a large amount of develop is supplied to a spot where the developer is not repelled by photoresist, which causes the occurrence of another problem that the developer was wasted much.
It is therefore an object of the invention to provide a photoresist developing nozzle, a photoresist developing apparatus, and a photoresist developing method capable of effecting a uniform development with less waste of developer even if a large diameter wafer has been used.
To achieve the above object, it is a first aspect of the invention to provide a developer supply nozzle comprising a nozzle body having a plurality of small chambers inside thereof, developer supply channels for supplying developer to the respective small chambers, and developer discharge sections respectively provided in the small chambers to discharge developer supplied from the developer supply channels onto a wafer.
It is a second aspect of the invention to provide a photoresist developing method comprising the steps of moving a wafer horizontally, discharging developer from a plurality of developer discharge channels onto the wafer, while said developer discharge channels are arranged over a transfer surface of the wafer serving as a moving passage of the wafer, and discharging developer from a given number of developer discharge channels of a plurality of developer discharge channels to the wafer.
According to the photoresist developing method, the amount of developer to be discharged outside the wafer can be sharply reduced, and hence the amount of consumption of the developer can be economized.
It is a third aspect of the invention to provide a photoresist developing method comprising the steps of measuring a surface temperature of a wafer, discharging developer from a plurality of developer discharge channels onto the wafer, controlling discharging amount of developer for every channel of the plurality of developer discharge channels in response to the result of measurement of the surface temperature of the wafer.
According to these photoresist developing methods, it is possible to dispense with nonuniform development caused by affinity with developer on the surface of the wafer or variations in temperature on the surface of the wafer.